This invention relates to assemblages of fasteners and their manufacture, and, more particularly but not exclusively, to assemblages of fasteners which are dispensable by machine for the tagging and attachment of articles.
Many different types of fasteners have been used for the tagging and attachment of articles. One construction is described in U.S. Ser. No. 153,154, now abandoned. These fasteners were produced by molding an assemblage of individual fasteners, each with a thin filament interconnecting a cross bar with a head, and joined together by necks to a common runner bar. These fasteners can be dispensed using a gun as described in U.S. Pat. No. 3,103,666.
After the development of the fastener described in Ser. No. 153,154, it was discovered that these fasteners could be significantly and unexpectedly improved by being stretched as described in U.S. Pat. No. 3,444,597, which also describes the stretching of the individual fasteners of an assemblage simultaneously. Various methods for producing stretched fasteners are described in U.S. Pat. Nos. 3,380,122, 3,444,597, and 3,457,589. As described in those specifications, the assemblages of fasteners are molded with slight tapers in a portion of their filaments in order to ensure that the stretching will extend substantially to the junctions of the filaments with the cross bars. While the manufacturing methods described in these specifications provide suitable fasteners, they require an appreciable time interval, e.g. cycle time, between molding and the completion of stretching. In addition, while these methods are eminently suitable for easily stretchable crystalline materials, such as nylon, they are less suitable for relatively rigid crystalline materials such as polypropylene.
Another difficulty encountered with materials such as polypropylene is that the cross bars tend to be pulled forward at their junctions with filaments. This distortion of the cross bar can make the fasteners inoperative and produce jamming in dispensing devices.